Electric motor construction



July 20, 1965 c. G. YOUNG 3,195,466

ELECTRIC MOTOR CONSTRUCTION Filed May 25, 1959 2 Sheets-Sheet 1 July 20, 1965 c. G. YOUNG ELECTRIC MOTOR CONSTRUCTION Filed May 25, 1959 2 Sheets-Sheet 2 INVENTOR. Cecf/ G. Yog/N6 Maan/ef United States Patent M5466 ELECTRIC MTGR CNSTRUCTUN Cecil G. Young, Warren, Ohio, assigner, by mesne assignments, to H. K. Porter Company, Inc., Pittsburgh, Pa., a corporation of Delaware Filed May 25, 1959, Ser. No. 815,540 6 Claims. (Ci. 1533-57) My invention relates to electric motors, more particularly to an electric motor combined with a pump, and the principal object of my invention is to provide new and improved products of this character.

The motor .of my invention, and the pump combined therewith, are notable in construct-ion in that no packing joint is provided on the shafts of either the motor or pump and this is advantageous because of the known unreliability of packing joints. Accordingly, the construction of my invention may be referred to as a hermetic pump motor and is characterized by the fact that the pump casing is connected directly with the motor casing and the interiors of the two are in communication.

My invention relates to an electric motor having a canned stator and rotor and embodies a novel bearing construction which maintains concentricity of the motor parts despite wear in the bearings. The motor and pump combination, at least in part because of the foregoing advantages, is ideally suited for pumping fluids of a toxic, precious, corrosive, or like nature, because losses through the shaft seal of the prior art is avoided.

In the drawings accompanying this speciiication and forming a part of this application, there are shown, for purposes of illustration, several embodiments which my invention may assume and in these drawings:

FIGURE y1 is a central longitudinal sectional view through a motor-pump combination illustrating an embodiment of my invention,

FIGURE 2 is an enlarged, fragmentary sectional View of parts disclosed in FIGURE l, and

FIGURE 3 is a central longitudinal sectional view through a motor-pump combination illustrating another embodiment of my invention,

Referring particularly to FIGURES l and 2, the embodiment therein disclosed comprises an electric motor and a` pump 11. The pump, as herein disclosed, comprises a volute housing 12 having a central inlet 14 and a peripheral discharge (not shown).

An impeller 15 of any suitable design is disposed for rotation within the pump housing 12 and has a hub 16 adapted to be suitably connected to one end of the motor shaft 17. The impeller 15 has a tubular forward r portion 18 through which fluid is drawn by the impeller 1S from the inlet 14 and is discharged, by action of the impeller, under pressure through the pump discharge.

Wearing rings 19 and 2t) are disposed respectively between the impeller hub 16 and pump housing and between the impeller portio-n 18 and pump housing. rI`he wearing rings are usually pressed into seats formed in the pump housing and provide a close clearance with the impeller to restrict recirculation of lthe iiuid between pump outlet and inlet. In the present embodiment, the rings i9 and 20 are formed of carbon.

In the embodiment herein disclosed, the pump housing 12 has a concentric extension 21 integrally connected to an end plate 22, the latter being connected in fluidtight relation withY an end plate 23 which comprises a part of the casing of motor 10. The end plate 22 has acircular opening in which a plate 43 is held, as by bolts 44. The plate 43 has a circular central opening v for the close passage of a tubular bearing support 25,

the latter having a large inner opening at one end and a smaller opening at the impeller end. The smaller ice opening has a stepped surface for receiving the bearing 19.

The exterior surface of bearing support 25 at its impeller end car-ries a band 26 to which is welded, or otherwise suitably secured, a plate 27 which forms a dening wall of the pump housing 12. The band 26 may be removably held to the support 25 by set screw (not shown) or in any other suitable manner. The plate 27 is provided with a plurality of openings 2.8 for the passage of pumped uid from the impeller housed portion of the pump 'housing to a rather large space 29 -formed by the plate 27, the plate 43 and the peripheral wall 2l, and the plate 27 contines turbulence of fluid to the zone near the impe-ller for improved hydraulic efficiency.

The motor liti, as herein illustrated, comprises a cylindrical shell 3d and end plates 23 and 3i, the end plates respectively itting opposite ends of the shell by means of stepped connections 32. A plurality of tie bolts 33 (only one visible in FIGURE l) pass through openings in the end plates 23 and 3l, the bolts having a head bearing against the outer surface of the plate 3l and an extremity threaded into the opening in plate 23, to tightly draw the end plates against opposite ends of the shell 3).

An auxiliary end plate 34 is bolted against the outside surface of the plate 31, and a tubular bearing support 3S is welded, or otherwise suitably secured, to the plate 34 and extends from opposite sides thereof.

A laminated stator 36, and field coils 37 are supported within the shell Se, the stator having a central opening 38 and a stator shell 39 passes through such opening and extends from opposite sides of the stator. The stator shell may be formed of any suitable material to accomplish the function of canning the stator and, in cases where corrosive uid is pumped, the stator shell is preferably formed of stainless steel.

As seen in FIGURES 1 and 2, opposite ends of the stator shell closely pass through central openings in the 'end plates 23 and 31. Each end plate has an outwardly directed circular rib 40 which is welded, as seen at 41, to the respective end of the stator shell 39 to thus seal the stator laminations 36 and the windings 37 against contact with any fluid which may enter the interior of the stator shell 39.

rEhe auxiliary end plate 34 has an inwardly directed circular rib 42 (see FIGURE 2) which closely fits within a circular recess formed in the end plate Si for the purpose of accurately locating the end plate 34 in centered relation with the axis of the motor.

The end plate 23 has a welded connection with the adjacent end of the stator shell 39 in like manner and this end plate has an annular recess in its outwardly facing side to receive a circular rib on plate 43 which forms a ide wall of the chamber 29. Bolts 44 are provided for detachably connecting the plates 34 and i3 to their re spective end plates 31 and 23. The plate 43 has a plurality of openings 45 to meter fluid ow from the chamber 29 to the interior of the stator shell 39.

A laminated rotor Sii is connected to and carried by the motor shaft i7, and a cylindrical rotor shell 51 closely encompasses the rotor Si) and is utilized to can the rotor, that is, to shield it from contact with fluids within the stator shell 39.

Bearing means are disposed between the motor shaft il? and the mototr casing, and, as herein illustrated, each bearing means comprises a frustum-shaped member 52 and a cooperating bearing member 53 which has a conical recess closely receiving the inclined side wall of the respective frustum-shaped member 52. Each member 52 is firmly iiXed to the shaft 11.7, as by a press t, or by welding, so that the connection therebetween is fluid tight.

Each member 52 as best seen in the left hand member illustrated in FIGURE 2, is formed with an out- Wardly directed circular rib 54 which closely tits within the respecitve end of the rotor shell l and is welded thereto, as shown at 55. The shell 5l is preferably made of stainless steel when the fluids pumped are of a corrosive nature. As best seen in FIGURE 2, the louter diameter of the rotor shell 5l is slightly less than the V:inner diameter of the stator shell 39 to maintain a very vsmall air gap and operating clearance which, in the present case is about .020 inch.

With the small operating clearance between the s-tator and rotor shells, it is essential th-at the stator an-d rotor `be maintained concentric despite bearing wear, and the tapered bearings herein illustrated maintain such ooncentricity, as will be apparent from the present and subsequent description.

The bearing member 53 at the right hand side .of FIG- URE 1 has a cylindrical exterior which closely tits withv:in the larger inner opening of the tubular support 25 and has a Hat bottom bearing against a at transverse wall of the support. A pin 60 seating within aligned vopenings .in the lfla-t bottom and transverse wall may be utilized to insure that the bearing member 53 is held against rotation within the tubular support. t The bearing member 53 at the left hand side lof FIG- URE l has .a cylindrical exterior which closely but slidably ts within the interior of bearing support 35. A cylindrical backing plate 61 also closely but slidably tits within the bearing support and has a ila-t transverse surface which bears against a flat surface of the bearing member 53. A pin 62 fitting within aligned openings in the backing plate and bearing member maybe -utiliZed to insure that the latter is held against rotation Within its support. The bearing plate 6I may be formed with an elongated slot 63 which receives a pin 64 carried by the bearing support 3'5 to hold the bearing plate 'against rotation.

To insure proper fit between the bearing surfaces of the two pairs of bearing members 52, 53, the members are spring pressed to maintain bearing t despite bearing wear. Since the bearings have conical bearing surfaces which are initially disposed concentric with the motor shaft, bearing we-ar is taken up by relatively moving coopera-ting bearing members 52, 53 in an axial direction and .toward each other.

eIn the presently disclosed embodiment, the backing plate 61 .has a central recess 65 which receives one end of a coil spring 66. The opposite end of the spring is received within a cap -67 secured to an inner end of a rod 68. The outer end of the tubular bearing support 35 yis closed by a transversely extending disc 69 which is welded or otherwise suitably secu-red to the support. The rod 16S extends through a packing gland 70 carried by the clos-ure disc 69 and its outer extremity be-ars `against the end of an adjusting stud 7l.

The stud 7l is threaded through an opening in a Support plate 72 and a plurality of screw studs 73 hold the plate 72 in spaced relation from the disc 69. It will be appreciated that the urging force of the spring may be varied by adjustment of the adjustment stud 7l. In some cases, the adjustment for the spring 66 may be omitted and a spring of known force interposed between .the backing plate 61 and a transverse stop fixed within the bearing support 35. In some cases it may 'be desirable -to indicate or observe bearing wear and for that purpose a rod 75, or the like, may have one end bearing against the backing plate 6l and its opposite end extending through .a packing lgland 76 carried by the closure vdisc 69. The outer extremity of the rod 7S may carry suitable measurement indicia '77 which may be noted from time to time to record bearing wear.

From the foregoing, it will be evident that the bea-ring member 5-3 (lett hand side of FIGURE l) is urged against its cooperating frustum-sh-aped member 52. Since the members 52 arerigidly secured t-o the vmotor shaft ll', the entire rotor assembly is urged to the right, as

i viewed in FIGURE l, and Vtherefore the right hand frustum-shaped member 52 is urged into bearing engagement within the conical recess in the corresponding member S3. Thus, despite bearing wear, concentricity of the various motor parts is maintained.

The lbearing par-ts 52, 53 are preferably of dissimilar materials and, in the present embodiment, the members )53 are formed of carbon and the members 52 formed of stainless steel since these materials form ideal coopera-ting bearing members which have long life and require little maintenance and lubrication. The fact that the bearing members 53 are closely received within their respective bearing supports 25 and 35 is important since the members 53 are protected against fracture which :might otherwise be brought about by the axial pressure on the bearings.

Since my invention provides a hermetically connected pump and motor, and since the motor has a canned rotor and stator, pumped tluid may be safely circulated through the motor to cool it and under certain circumstances provide lubrication for the bearings.

In the presently `disclosed embodiment, a portion of .the pumped iluid from the impeller housing is passed through openings 2.8 `and 45 to the interior of the stator shell 39 and iills the space `titl adjacent the right hand bearing assembly. Any fluid which passes from space 30 downwardly along the conical bearing surfaces may flow along the exterior surface of the shaft 17 and return to the low pressure area at the center of the pump impeller through openings 8l in the hub of the impeller, and because of the differential in pressure .a tendency to circulate lluid lin this path is induced, although the bearings may not always, if at all, permit such circulation of Huid.

The uid from space 80 may also pass through the operating or air gap between the stator shell 39 and Yrotor shell 5l and pass to a similar space 82 adjacent to the lef-t hand bearing assembly. /At this latter assembly, uid may pass along cooperating bearing surfaces :and escape through :a central opening 83 in the bear-ing plate 61 to the space `841 within the tubular bearing support 35, However, a greater portion `of the tluid from space 82 flows through a pipe 85 which has one end communicating with the space 82 and its other end communicating with the s-pace 84. An exhaust pipe 86 m-ay convey fluid from the space 84 back to the inlet 14 i of the pump `1l..

The embodiment of my invention shown in FIGURE 3 is somewhat similar to that previously described, certain distinctions being that two pumps are ad-apted to be driven by respective opposite ends of the motor Shaft and that Belleville washers are used to spring-load each bearing assembly. Apart from the distinctions, cor-responding parts will be designated in the embodiment of FIGURE 3 by the same reference numerals supplemented by the .sutiix LL yThe motor shaft 17a in this embodiment supports an impeller 15a .at each end (only one impeller being shown in FIGURE 3) and such impeller .rotates within a housing `ll2a :as before. The metering and support plates 43a vare bolted to respective end plates' 23a and are maintained concentric by having a circular periphery closely titting a circular recess in the respective end plate.

A cylindrical bearing support 90 is Welded to each plate 43a interiorly of the motor casing and a collar Y 91 is welded to each support plate 43a exteriorly of .the motor casing. Each collar 91, as before, supports a 'plate 27a.

A bearing member 53a is closely received Within each bea-ring support 90 and has a at protective washer 92 ,bearing against its flat transverse surface. Pins 93, 94 Vmay be used Ito hold the bearing members 53a against rotaion. A series of Belleville spring washers 95 is interposed between each washer 92 and the adjacent Hat surface of respective collar 91, each Belleville spring assembly urging i-ts lbearing mem-ber to engagement with the cooperating bearing member 52a.

In the embodiment disclosed in FIGURE 3, the springs at opposite ends of the shaft provide for shaft thrust in either direction which may result from different pumping conditions at the two pumps. It will be noted that the rotor 59a is wider than the stator 36a to maintain proper operating relations between the two regardless of the fact that the shaft 17a which carries the rotor has shifted axially a slight amount due to any unbalance in pumping conditions. As before, the bearing members 52a are preferably of stainless steel to resist corrosion and the bearing members 53a are of carbon since this material is inert and non-corrosive, is capable of withstanding high tempera- Y tures, and is unaffected by acids, alkalis and the like, and

contains nothing which will dissolve or otherwise separate therefrom. It will be appreciated that the bearing members 52, 53 may be made of any materials suitable for and required by the characteristics of the fluid being pumped.

It is presently preferred to use the Belleville spring as the urging force maintaining the bearings vin proper relationship because of the characteristics of such springs. For example, a desirable characteristic of Belleville springs is that once the spring washer (or washers) approach a flat condition, the spring rate becomes substantially constant, thereby giving substantially constant spring force generally independent of position. This is very desirable from a bearing loading standpoint.

As before, pumped fluid is permitted to circulate through the motor and the latter has a canned rotor and stator to protect these parts from the fluid.

With pumping pressures equal in both pumps, fluid from either casing 12a will pass through openings 28a.

, Since the pressures are equal, no fluid flow will exist in the gap between the stator and rotor shells 39a and 51a. Accordingly, fiuid flow is induced along the bearing surfaces to return through the opening in the impeller hub and back to the respective pump inlet.

It may be preferable to have different pressures at the two pumps so that fluid flow is induced from the pump of higher pressure, through the motor and to the pump of lower pressure. However, in this instance, care must be taken to pump fluids which may be mixed. In some cases, it may be desirable to provide small lubrication grooves in either the member 52 or member 53 to facilitate flow of fluid through the bearing.

In view of the foregoing it will be apparent to those skilled in the art that I have acomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiments herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it Will be appreciated that the herein disclosed embodiments are illustrative only, and that my invention is not limited thereto.

l claim:

1. An electric motor, comprising a housing including a tubular shell and end plates closing opposite ends of said shell, a cylindrical sleeve extending longitudinally within said shell and having its opposite ends connected to respective end plates and providing a sealed tubular space between the outer surface of said sleeve and the interior surface of said shell, a pair of tubular bearing supports each rigidly secured to and extending from a respective end plate, a conically recessed bearing mounted within each bearing support with the recesses facing each other, at least one of said bearings being movable axially within its support, the rigid securement of said bearing supports and the mounting of said bearings cooperating to maintain said bearings in spaced alignment on a common axis which is coaxial with the axis of said cylindrical sleeve, a rotor concentric with and located within said sleeve for rotation therein, said rotor having an outer cylindrical surface slightly smaller than the inner surface of said sleeve to provide an annular gap therebetween of very small magnitude to separate the rotor from said sleeve and stator and yet provide a free flux path for efficient transmission of magnetic flux from said stator to said rotor, oppositely facing cone-shaped journals on and coaxial with said rotor and fitting complementarily within respective conical recesses, and resilient means for urging said coneshaped journals and the surfaces defining said conical recesses together in coaxial manner so that any bearing wear is coaxial with said rotor and thus will not affect concentricity of the latter with respect to said cylindrical sleeve and thereby ymaintain said annular gap.

2. The construction according to claim 1 and further including a pump casing joined to said motor housing, and means establishing free flow of the pumped fluid from said pump casing to the interior of said cylindrical sleeve.

3. The construction according to claim 2 wherein an end of said cylindrical sleeve opens into said pump casing, and a plate spans such open end and has metering openings therein to provide a regulated ow of material from said pump casing to said sleeve interior.

4. The construction of claim 1 wherein both of said bearings are movable axially Within their tubular supports and wherein Belleville washers press each of said bearings against respective cone-shaped journal surfaces of said rotor.

5. An electric motor-pump unit, comprising a rnotor housing including a tubular shell and end plate means closing opposite ends of said shell, a cylindrical sleeve extending longitudinally within said shell and having opposite ends sealed to respective end plate means, at least one of said end plate means having an opening communicating with the interior of said sleeve, a motor stator within the space between the exterior of said sleeve and the interior of said tubular shell, a motor rotor concentric with and located within said sleeve for rotation therein, said rotor having an outer cylindrical surface slightly smaller than the inner surface of said sleeve to provide an annular gap therebetween of very small magnitude to separate the rotor from said sleeve and stator and yet provide a free flux path for efcient transmission of magnetic iiux from said stator to said rotor, a pair of tubular bearing supports within said sleeve, each rigidly connected to and extending inwardly of respective end plate means, a bearing mounted within each bearing support, each bearing having a conical recess coaxial with said cylindrical sleeve, at least one of said bearings being movable axially within its support, and said conical recesses facing each other, the rigid securement of said bearing supports and the mounting of said bearings cooperating to maintain said bearings in spaced alignment on a cornmon axis which is coaxial with the axis of said cylindrical sleeve, oppositely facing cone-shaped journals fixed on and coaxial with said rotor and fitting complementarily within respective conical recesses, resilient means for urging said cone-shaped journals and the surfaces delining said conical recesses together in coaxial manner so that any bearing wear is coaxial with said rotor and thus will not affect the concentricity of the latter with respect to said cylindrical sleeve, thereby maintaining said annular gap, a pump casing having an open back wall connected in fluid-tight relation with said one end plate means and communicating with the interior of said sleeve through the opening in said one end plate means, an impeller within said pump casing, said rotor having a shaft which extends through said one end plate means and into said pump casing and to which said impeller is secured.

6. The construction of claim 5 wherein both of said end plate means have an opening therein communicating with the interior of said sleeve at respective opposite ends thereof, and wherein an open back pump casing is conneected in fluid-tight relation with each end plate means, each pump casing having communication with the interior of said sleeve through the opening in the References Cited by the Examiner UNITED STATES PATENTS Olson 308-70 Hubbard 308-70 X Huffman 308-71 Stover 308-70 Litzenberg 103-87 Cametti et al 310-88 X 8 2,906,208 9/59 White 103-87 2,925,041 2/ 60 Sigmund 103-87 3,114,322 12/63 Leonard 10S-87 FOREIGN PATENTS 5 586,760 3/47 Great Britain. 724,737 2/55 Great Britain.

References Cited bythe Applicant lo UNITED STATES PATENTS 2,722,805 11/55 Leonard.

LAURENCE V. EFNER, Prmfzy Examiner.

MILTON O. HTRSHETELD, ROBERT M. WALKER, 15 JOSEPH H. BRANSON, 1R. Examiners. 

1. AN ELECTRIC MOTOR, COMPRISING A HOUSING INCLUDING A TUBULAR SHELL AND END PLATES CLOSING OPPOSITE ENDS OF SAID SHELL, A CYLINDRICAL SLEEVE EXTENDING LONGITUDINALLY WITHIN SAID SHELL AND HAVING ITS OPPOSITE ENDS CONNECTED TO RESPECTIVE END PLATES AND PROVIDING A SEALED TUBULAR SPACED BETWEEN THE OUTER SURFACE OF SAID SLEEVE AND THE INTERIOR SURFACE OF SAID SHELL, A PAIR OF TUBULAR BEARING SUPPORTS EACH RIGIDLY SECURED TO AND EXTENDING FROM A RESPECTIVE END PLATE, A CONICALLY RECESSED BEARING MOUNTED WITHIN EACH BEARING SUPPORT WITH THE RECESSES FACING EACH OTHER, AT LEAST ONE OF SAID BEARINGS BEING MOVABLE AXIALLY WITHIN ITS SUPPORT, THE RIGID SECUREMENT OF SAID BEARING SUPPORTS AND THE MOUNTING OF SAID BEARINGS COOPERATING TO MAINTAIN SAID BEARINGS IN SPACED ALIGNMENT ON A COMMON AXIS WHICH IS COAXIAL WITH THE AXIS OF SAID CYLINDRICAL SLEEVE, A ROTOR CONCENTRIC WITH AND LOCATED WITHIN SAID SLEEVE FOR ROTATION THEREIN, SAID ROTOR HAVING AN OUTER CYLINDRICAL SURFACE SLIGHTLY SMALLER THAN THE INNER SURFACE OF SAID SLEEVE TO PROVIDE AN ANNULAR GAP THEREBETWEEN OF VERY SMALL MAGNITUDE TO SEPARATE THE ROTRO FROM SAID SLEEVE AND STATOR AND YET PROVIDE A FREE FLUX PATH FOR EFFICIENT TRANSMISSION OF MAGNETIC FLUX FROM SAID STATOR TO SAID ROTOR, OPPOSITELY FACING CONE-SHAPED JOURNALS ON SAID COAXIAL WITH SAID ROTOR AND FITTING COMPLEMENTARILY WITHIN RESPECTIVE CONICAL RECESSES, AN RESILIENT MEANS FOR URGING SAID CONESHAPED JOURNALS AND THE SURFACES DEFINING SAID CONICAL RECESSES TOGETHER IN COAXIAL MANNER SO THAT ANY BEARING WEAR IS COAXIAL WITH SAID ROTOR AND THUS WILL NOT EFFECT CONCENTRICITY OF THE LATTER WITH RESPECT TO SAID CYLINDRICAL SLEEVE AND THEREBY MAINTAIN SAID ANNULAR GAP. 